Codec Crazy


Carina is getting me the Mvix MX-760HD wireless HD media center for Christmas. I’ve long wanted some kind of low-profile media center, so I can rip DVDs and CDs and avoid all the mess of physical media; but I’ve been extremely picky on form factor in regular PCs, and just plain lazy about getting around to trying MythTV. Plus, I’ve been too frugal to actually purchase anything.

In anticipation of the device, I started re-educating myself about the options available to me for transferring and compressing DVD video to other formats. On my PowerBook, I can use Handbrake easy enough; and on my GNU/Linux laptop I can use avidemux. Handbrake is by far easier to use, but as a trade-off I lose some control. (Each is available for the other platform, incidentally.)

For example, I have a few Star Trek TNG episodes (and Space Ghost, and Sea Lab 2021, and Mystery Science Theater 3000…) on DVD that I’d like to convert for eventual storage on the media center. Handbrake makes it trivial to rip the individual episodes to discrete .mp4 files, but it copies the whole episode. I don’t particularly need the opening credit sequence – which is usually the same every time – in every file, but Handbrake does not give me the option to remove that. I can remove the credit sequence using Avidemux, but I’m not entirely sure that the resultant file is as good as those produced by Handbrake, namely because I’m required to twiddle quantizer and encoding options about which I know nothing.

A movie ripped by Handbrake is identified by the file utility as “ISO Media, MPEG v4 system, version 2”, whereas a file ripped by Avidemux is identified as “ISO Media, MPEG v4 system, version 1”. I don’t entirely know what the differences are, nor whether I should care. Making things even more confusing to me, Avidemux supports two different MPEG-4 codecs: libavcodec and Xvid. When using libavcodec, I usually get errors about the second pass settings I’ve selected, so I end up using Xvid. What’s more, I can’t get Avidemux to produce an .mp4 file with sound if I select the “MP4” container format; instead I need to select an AVI format. So I’ve got MP4 video with AC3 audio inside an AVI container: file reports “RIFF (little-endian) data, AVI, 720 x 480, ~30 fps, video: XviD, audio: Dolby AC3 (6 channels, 48000 Hz)”. I have no idea if that’s ideal or not.

I tried feeding the MP4 file from Handbrake into Avidemux, but that didn’t seem to work any better (encoding an already lossy encoded file seems sub-optimal, even if it works). I’m tempted to give up, use Handbrake for convenience, and just keep the credit sequences.

Anyone have any encoding advice they’d like to share?

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